Brush grinder tool



March 28, 1950 G. E. DlEZ BRUSH GRINDER TOOL 2 Sheets$heet 1 Filed April 6, 1949 diflfliez INVENTOR BY I 1 ATTORNEYS.

G. E. DlEZ BRUSH GRINDER TOOL March 28, 1950 Filed A ril 1949' 2 Sheets-Sheet 2 .Jiez

INVENTOR ATTORNEYS.

Patented Mar. 28, 1950 attract UNITED STATES PATENT OFFICE 2,501,891 BRUsii GRINDER "r001.

George E.'Diez, Herrin, 111. Application April 6, 1949, Serial No. 85,930

1 frhis invention relates w a 1:601 for" grinding the brushes of electric motors.

In the grindingotbru'shes, it is common industry practice to remove the old brush from the motor, place a newbrushin the holder on the motor, raise thenew brush in the holder, and then, 'after placing a strip of sandpaper cut slightly wider than the width of the brush'under thebrush, sandpaper the end of thebrush manually until thebrush' is fitted to 'the contour 'of the commutator.

v "This practice is quite tedious; in view of the fact that there is a considerable'portion of the brush which r'nu'stbe ground away by manual reciprocationof the sandpaper strip.

Accordingly, it'is an important Object of the present invention to provide a brush grinder whichwill eliminate the necessity of manual grinding ofa'brush'to fit the contour of a particular commutator. 7

Another important object'is to providea device which will accomplish the above stated purpose, and which will'nevertheless' be inexpensive, durable,"a'nd which will have a high degree or accuracy.

'Another"iiriportantobject is to provide a device which, when set for the grinding of one brush, will remain set for the grinding of other brushes to the same'contour.

Still another object is to provide a device of the type stated which will permit the brushes to be groundwith speed and ease, and by'per'sons having comparatively little skill and experience in electric motor repair.

With the foregoing and other objects in view which will appear as the description proceeds, the invention consists of certain novel details of con'struction and combinations'of parts hereinafter more fully described and pointed out in the claims, it being understood that changes may be made in the construction and arrangement of parts without departing from the spirit of the invention as claimed.

Referring to the drawings Figure 1 is a front elevational view of a brush grinder constructed in accordance with the invention.

Fig. 2 is a top plan view.

Fig. 3 is a rear elevation.

Fig. 4 is a section on line 4-4 of Fig. 2.

Fig. 5 is a fragmentary bottom plan view.

Referring to the drawings in detail, a flat disc 5 is integrally formed with the hub 6 threaded to receive the collar 1' whereby there can be secured to the disc for rotation therewith a piece of abra- Claii'ns. (01. 51-125) slot 2| through which the screw it extends.

sive material 8 such as sandpaper. Extending from the hub and rotatable with the disc is the stubshaft 9, and rotation'of the disc can be accomplished by means of crank handle Ill. Of course; instead of the crank handle Hi, rotation of the disc can be accomplished by such power ine'ans as an electric motor.

The stub shaft 9 is rotatable within a sleeve I I, and the sleeve and stub shaft are also relatively slidabie in the direction of their lengths.

' Extending laterally from one end of the sleeve is the handle 52 which is rigid with the sleeve as for example by the provision of an opening in the sl'ee've in which is press fitted the reduced end i3'of the handle.

Diametrically opposite thehaiidle i2 and also rigid with the sleeve H is the spindle I4 extending from the medial'portion'of the sleeve, and mounted upon the spindle is a bracket it formed at one end with oppositely extended ears IE, IT, through which extend screws I8, i9 that are threaded into a brush holder 26 U-shaped in cross section.

Formed in the upper ear [5 is a short arcuate y reason of this construction, means are provided for relating the brush holder 26 and bracket I5 at selected angles to each other. So that an exact angular relationship can 'be established, I provide the degree-marked scale 22 on the brush holder, with which cooperates the index 23 marked upon the bracket. Thus, if a particular angle setting is desired, the user loosens the screw [8, thus permitting the brush holder 20 to'pivot upon the screw l9. After the brush holder has been moved to the selected angle, as for example 10, the screw i8 is again tightened, so as t6 held the brush holder 26 and the bracket [5 against relative movement after said setting has been made.

The making of this angle setting will cause the brush holder 20 to be set at a predetermined angle relative to the face of the grinding disc 5.

I also provide for angularly relating the brush holder to the face of the disc in a plane perpendicular to the plane in which it was inclined in making the first angle setting. To this end, I split the opposite end of the bracket It: as shown at 24, and mount on the split end the clamping screw 25. Thus, by loosening the clamping screw 25, the bracket I 5 can be rotatably adjusted upon the spindle H. (see Fig. 4). A degree scale 26 is provided upon the bracket i5, cooperating with index 2'! marked upon the spindle [4. Therefore, rotary adjustment of the bracket (and therefore the brush holder 20) can be effected upon the spindle, and when adjustment has been made to a prescribed degree setting, as for example on the degree scale 26, the clamping screw 25 is tightened to hold the bracket against movement relative to the spindle i4 after the setting has been made.

Mounted upon the brush holder is the U-clamp 2B, and carried by the U-clarnp is the presser foot 29 threadable through a block that is slidable in a slot 3| extended transversely of the U-clamp 28.

The presser foot 29 is adapted to be threaded against a brush B to be ground, said brush being positioned against one side of the holder 20 so that when clamped in position by the presser foot 29, it will assume the same angular relation to the abrasive disc as possessed by the brush holder.

The use of the device may now be noted. Shaft 9 is withdrawn from the sleeve ii if desired to replace sandpaper 8. The old brush is now removed from the motor generator, and is placed edgewise on a scale 31 marked on the under side of disc 5, and constituting a matching scale. By placing the old brush edgewise on this scale, an angle reading is obtained which is to be used in grinding a bevel on the brush (see Fig. 4). This reading is utilized by adjusting bracket i5 upon spindle [4, the same number of degrees, as for example 10 and securing said bracket and spindle in their adjusted relation.

The old brush is now placed again upon the scale 3| but on this occasion is positioned fiatwise rather than edgewise. This will provide a reading in degrees of the taper of the commutator to which the brush will be applied when mounted in the motor. Accordingly, screw it is loosened, and brush holder 20 is pivotally adjusted the proper number of degrees and screw it is again tightened. Therefore, when the brush B is mounted in the brush holder 20, it will have been set for taper (see Figs. 1 and 2).

In some instances, the commutator is not tapered, and it will be understood that on these occasions, the scale 22 and index 23 are set at 0.

After these settings have been made and the parts tightened, the sleeve II is mounted upon the spindle 9. In this connection, the new brush B is so clamped to the brush holder 20, initially, as to space the lower end of the sleeve l i a short distance above the collar 1. This is to allow for that portion of the lower end of the brush B which will be ground ofi during the operation.

When the parts have all been positioned as in Fig. 1, the user grasps the handle l2 in one hand, and rotates the disc 5 by means of the crank handle ID with the other hand. The brush B will now be ground with full accuracy to fit the particular commutator.

If other brushes are to be ground to the same contour, it is necessary only to loosen the presser foot 29 and insert additional brushes to be ground in succession, without changing the angle settings.

What is claimed is:

1. A brush grinder comprising an abrasive disc, a stub shaft rotatable therewith, a sleeve slidable and rotatable on the stub shaft, a handle rigid with the sleeve, a spindle rigid with the sleeve, 2. brush holder mounted upon the spindle, and means for adjustably positioning the brush holder upon the spindle for setting the brush holder at a predetermined angular relationship relative to the abrasive disc.

2. A brush grinder comprising an abrasive disc, means for rotating the disc, a stub shaft extending from and rotatable with the disc, a sleeve slidably and rotatably mounted upon the stub shaft, a handle rigid with the sleeve, a spindle rigid with and extended laterally from the sleeve, a bracket mounted for rotary adjustment upon the spindle, a brush holder mounted for pivotal adjustment upon the bracket, and means for securing the bracket and brush holder respectively in selected positions of adjustment.

3. A brush grinder comprising an abrasive disc, means for rotating the disc, a stub shaft extending from and secured for rotation with the disc, a sleeve slidable and rotatable upon the stub shaft, a holding handle extending from the sleeve, a lateral spindle extending from the sleeve, a bracket mounted for rotary adjustment upon the spindle, said spindle and bracket having co operating degree markings, means for clamping the bracket to the spindle in selected positions of rotary adjustment, a brush holder pivotally mounted upon the bracket, said brush holder and bracket having cooperating degree markings, means for clamping the brush holder to the bracket in selected positions of relative adjustment, and means for clamping a brush to the brush holder, said adjusting means of the bracket and brush holder adapted to relate a brush angularly to the abrasive disc for bevel and taper grinding of the brush.

GEORGE E. DIEZ.

REFERENCES CITED The following references are of record in the file of this. patent:

UNITED STATES PATENTS Number Name Date 422,204 Gold Feb. 25, 1890 1,377,884 Heryngfel et a1 May 10, 1921 

